The invention relates to a turbine blade of a gas turbine. In addition, the invention relates to a method for coating a turbine blade of a gas turbine.
A turbine blade of a gas turbine and a method for coating a turbine blade of a gas turbine are known from European Patent Document No. EP 1 111 192 B1, wherein the turbine blade has a blade pan, a blade root, and a platform positioned between the blade pan and the blade root. This prior art document proposed that the turbine blade be coated with a wear protective coating on a lower side of the platform and on a transition region between the lower side of the platform and the blade root, namely with an anti-corrosive protective coating, wherein the wear protective coating is a MCrAlY overlay coating. This overlay coating features a chromium content of between 10% by weight and 40% by weight.
Starting herefrom, the objective of the present invention is creating a novel turbine blade of a gas turbine and a novel method for coating a turbine blade.
According to the invention, the anti-corrosion coating is a diffusion coating having a chromium content in the surface region of more than 30% by weight.
The method according to the invention, in an embodiment, includes at least the following steps: a) making a turbine blade available; b) applying at least one lacquer coat to at least one region of the turbine blade, wherein the lacquer includes chromium particles and/or chromium alloy particles, halides, and a binding agent; c) drying the applied lacquer at a temperature between 50° C. and 600° C. with disintegration of the binding agent; and d) subsequent reactive connection at a temperature between 900° C. and 1160° C.
The present invention makes it possible for the service life of turbine blades to be increased and for an effective protection against hot-gas corrosion or sulfidation to be realized, wherein this protection with respect to the base material of the turbine blade is increased by the factor of 6. A good coating can be guaranteed even with a complex contouring of the lower side of the platform and of the transition region between the lower side of the platform and the blade root.
Preferred further developments of the invention are disclosed in the following description. Without being limited hereto, exemplary embodiments of the invention are explained in greater detail on the basis of the drawing.